What is the diagnosis and treatment of prolactinoma (Prolactin-secreting pituitary tumor)?

From the Guidelines

Treatment of prolactinoma should begin with dopamine agonist medications, with cabergoline being the first-line choice due to its superior efficacy and fewer side effects compared to bromocriptine, as recommended by the most recent consensus guideline for the diagnosis and management of pituitary adenomas in childhood and adolescence 1.

Key Considerations

• Dopamine agonists, such as cabergoline, work by mimicking dopamine, which naturally inhibits prolactin secretion, and are effective in normalizing prolactin levels and reducing tumor size in most patients 1.
• Cabergoline has a longer half-life and greater affinity for the dopamine receptor than other dopamine agonists, making it the preferred choice for treating prolactinomas 1.
• Treatment duration varies, but typically continues for at least 2 years with normal prolactin levels before attempting medication withdrawal, and regular monitoring includes prolactin level checks and periodic MRI scans to assess tumor size 1.
• Surgery is reserved for patients who don't respond to or cannot tolerate medication, or for those with severe visual impairment requiring immediate decompression, and radiotherapy may be considered in exceptional cases where other treatment modalities are not available or have been exhausted 1.

Monitoring and Side Effects

• Regular monitoring is essential to assess the effectiveness of treatment and potential side effects, which may include nausea, dizziness, and headaches, and can be managed with dose adjustments or switching to a different dopamine agonist 1.
• Echocardiography is recommended at the start of treatment with a dopamine agonist and yearly surveillance echocardiography for patients receiving high-dose cabergoline to monitor for potential cardiac valve regurgitation 1.
• Cerebrospinal fluid leak and apoplexy are rare but potential complications of dopamine agonist therapy, and patients should be monitored for these adverse effects 1.

From the FDA Drug Label

Bromocriptine mesylate tablets, USP treatment is indicated in patients with prolactin-secreting adenomas, which may be the basic underlying endocrinopathy contributing to the above clinical presentations. Reduction in tumor size has been demonstrated in both male and female patients with macroadenomas In cases where adenectomy is elected, a course of bromocriptine mesylate tablets, USP therapy may be used to reduce the tumor mass prior to surgery.

Prolactinoma Treatment: Bromocriptine mesylate tablets, USP are indicated for the treatment of prolactin-secreting adenomas, including macroadenomas. The treatment has been shown to reduce tumor size in both male and female patients. Additionally, bromocriptine mesylate tablets, USP may be used to reduce tumor mass prior to adenectomy 2.

From the Research

Definition and Diagnosis of Prolactinoma

• Prolactinoma is a type of pituitary tumor that secretes prolactin, commonly found in both female and male patients with abnormal sexual and/or reproductive function or with galactorrhea 3.
• If serum prolactin levels are above 200 microg/L, a prolactin-secreting pituitary adenoma (prolactinoma) is the underlying cause, but if levels are lower, differential diagnoses include the intake of various drugs, compression of the pituitary stalk by other pathology, hypothyroidism, renal failure, cirrhosis, chest wall lesions, or idiopathic hyperprolactinemia 3.
• The main investigations in the diagnosis of a prolactin-secreting adenoma are hormonal and radiological, including computerised tomography (CT) and magnetic resonance imaging (MRI) 4.

Treatment of Prolactinoma

• Medical therapy with dopamine agonists (DA) is the preferred initial treatment for the vast majority of patients harboring prolactinomas 5.
• The most commonly used dopamine agonists are bromocriptine, pergolide, quinagolide, and cabergoline, with cabergoline having the most favorable profile in terms of plasma half-life, efficacy, and tolerability 3.
• Cabergoline is very effective and well tolerated in more than 90% of patients with either microprolactinomas or macroprolactinomas, and induces tumor shrinkage in the majority of patients with macroprolactinomas 6.
• Pituitary surgery is indicated in patients who cannot tolerate or are resistant to therapy with DAs, patients that seek fertility and harbor adenomas that impinge on the optic chiasm, psychiatric patients with contraindication to DA treatment, and patients presenting with pituitary apoplexy or a cerebrospinal fluid (CSF) leak 5.

Management of Resistant Prolactinomas

• Dopamine agonist (DA)-resistant prolactinomas are rare but constitute a real challenge, with few therapeutic alternatives left for these patients 7.
• The addition of a somatostatin analog to ongoing cabergoline treatment may be effective in some patients with DA-resistant macroprolactinomas, independently of the adenoma's SSTR expression profile 7.
• Combination treatment with cabergoline and octreotide LAR resulted in a significant reduction in PRL concentrations and adenoma size in two out of five patients with macroprolactinomas 7.